1. The infrared and Raman spectra of cis- and trans-hexatriene were remeasured and reassigned. Past assignment(s) were shown to be slightly, but significantly, in error. 2. The lower Rydberg transitions of cis-hexatriene were studied in detail. Firm assignments were obtained for the 3p(A1) and 3d(A2) Rydberg states. The 3s, 3p-prime, 3d-prime and 4s states were also observed. 3. A synthesis of the effect of different types of substitutional perturbations on the lower Rydberg spectra of conjugated polyenes was constructed.